1,243 research outputs found
Investigation of fast initialization of spacecraft bubble memory systems
Bubble domain technology offers significant improvement in reliability and functionality for spacecraft onboard memory applications. In considering potential memory systems organizations, minimization of power in high capacity bubble memory systems necessitates the activation of only the desired portions of the memory. In power strobing arbitrary memory segments, a capability of fast turn on is required. Bubble device architectures, which provide redundant loop coding in the bubble devices, limit the initialization speed. Alternate initialization techniques are investigated to overcome this design limitation. An initialization technique using a small amount of external storage is demonstrated
UK/US naval interoperability collaborative rersearch
This paper outlinees a collaborative program being carried out under an agreement between the US and the UK which started in January 2000, and is due to continue for four years. The research and is looking at the operational problems of coalition force interoperability initial from a naval perspective at the command and combat system level but then moving to a wider domain to cover both land and air participation. Details are given of why the research is necessary, the objectives and the approach being adopted. It then provides some information on the experiences gain from the initial trials which have been carried out during the first six months of this year
Rapid Effective Trace-Back Capability Value in Reducing the Cost of a Foot and Mouth Disease Event
This study evaluates how the availability of animal tracing affects the cost of a hypothetical Foot and Mouth Disease (FMD) outbreak in the Texas High Plains using alternative tracing scenarios. To accomplish this objective, the AusSpread epidemic disease spread model (Ward et al., 2006) is used to simulate a High Plains FMD outbreak under different animal tracing possibilities. A simple economic costing module (Elbakidze, 2008) is used to determine the savings in terms of animal disease mitigation costs from rapid, effective trace-back. The savings from increased traceability are then be compared to the cost of a functional National Animal Identification System (NAIS). Initial results indicate that rapid, effective tracing reduces the overall cost of disease outbreaks and that the benefits per animal in terms of reduced cost of an outbreak more than outweigh the annualized cost per animal of implementing a NAIS. A value of time related to controlling an outbreak is estimated to have increased benefits from an identification system that incorporates a rapid response capability. We also find the level of benefits vary depending on the location of initial infection and whether or not welfare slaughter occurs.Traceability, Foot and Mouth Disease, Economics, Agricultural and Food Policy, Livestock Production/Industries,
1.3 mm Polarized emission in the circumstellar disk of a massive protostar
We present the first resolved observations of the 1.3 mm polarized emission from the disk-like structure surrounding the high-mass protostar Cepheus A HW2. These CARMA data partially resolve the dust polarization, suggesting a uniform morphology of polarization vectors with an average position angle of 57° ± 6° and an average polarization fraction of 2.0% ± 0.4%. The distribution of the polarization vectors can be attributed to (1) the direct emission of magnetically aligned grains of dust by a uniform magnetic field, or (2) the pattern produced by the scattering of an inclined disk. We show that both models can explain the observations, and perhaps a combination of the two mechanisms produces the polarized emission. A third model including a toroidal magnetic field does not match the observations. Assuming scattering is the polarization mechanism, these observations suggest that during the first few 104 years of high-mass star formation, grain sizes can grow from1 mm to several 10s μm.Fil: Fernandez Lopez, Manuel. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones CientÃficas. Instituto Argentino de RadioastronomÃa. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomia; ArgentinaFil: Stephens, I. W.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos. Boston University; Estados Unidos. University of Illinois; Estados UnidosFil: Girart, J. M.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos. Institut de Ciències de l’Espai; EspañaFil: Looney, L.. University of Illinois; Estados UnidosFil: Curiel, S.. Universidad Nacional Autónoma de México; MéxicoFil: Segura Cox, D.. University of Illinois; Estados UnidosFil: Eswaraiah, C.. National Tsing Hua University; República de ChinaFil: Lai, S. P.. National Tsing Hua University; República de Chin
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Reference-based analysis of lung single-cell sequencing reveals a transitional profibrotic macrophage.
Tissue fibrosis is a major cause of mortality that results from the deposition of matrix proteins by an activated mesenchyme. Macrophages accumulate in fibrosis, but the role of specific subgroups in supporting fibrogenesis has not been investigated in vivo. Here, we used single-cell RNA sequencing (scRNA-seq) to characterize the heterogeneity of macrophages in bleomycin-induced lung fibrosis in mice. A novel computational framework for the annotation of scRNA-seq by reference to bulk transcriptomes (SingleR) enabled the subclustering of macrophages and revealed a disease-associated subgroup with a transitional gene expression profile intermediate between monocyte-derived and alveolar macrophages. These CX3CR1+SiglecF+ transitional macrophages localized to the fibrotic niche and had a profibrotic effect in vivo. Human orthologs of genes expressed by the transitional macrophages were upregulated in samples from patients with idiopathic pulmonary fibrosis. Thus, we have identified a pathological subgroup of transitional macrophages that are required for the fibrotic response to injury
Bubble memory module for spacecraft application
Bubble domain technology offers an all-solid-state alternative for data storage in onboard data systems. A versatile modular bubble memory concept was developed. The key module is the bubble memory module which contains all of the storage devices and circuitry for accessing these devices. This report documents the bubble memory module design and preliminary hardware designs aimed at memory module functional demonstration with available commercial bubble devices. The system architecture provides simultaneous operation of bubble devices to attain high data rates. Banks of bubble devices are accessed by a given bubble controller to minimize controller parts. A power strobing technique is discussed which could minimize the average system power dissipation. A fast initialization method using EEPROM (electrically erasable, programmable read-only memory) devices promotes fast access. Noise and crosstalk problems and implementations to minimize these are discussed. Flight memory systems which incorporate the concepts and techniques of this work could now be developed for applications
The immediate environment of the Class 0 protostar VLA1623, on scales of ~50-100 AU, observed at millimetre and centimetre wavelengths
We present high angular resolution observations, taken with the Very Large
Array (VLA) and Multiple Element Radio Linked Interferometer Network (MERLIN)
radio telescopes, at 7mm and 4.4cm respectively, of the prototype Class 0
protostar VLA1623. At 7mm we detect two sources (VLA1623A & B) coincident with
the two previously detected components at the centre of this system. The
separation between the two is 1.2arcsec, or ~170AU at an assumed distance of
139pc. The upper limit to the size of the source coincident with each component
of VLA1623 is ~0.7arcsec, in agreement with previous findings. This corresponds
to a diameter of ~100AU at an assumed distance of 139pc. Both components show
the same general trend in their broadband continuum spectra, of a steeper dust
continuum spectrum shortward of 7mm and a flatter spectrum longward of this.
We estimate an upper limit to the VLA1623A disc mass of <0.13Msol and an
upper limit to its radius of ~50AU. The longer wavelength data have a spectral
index of \alpha~0.6+/-0.3. This is too steep to be explained by optically thin
free-free emission. It is most likely due to optically thick free-free
emission. Alternatively, we speculate that it might be due to the formation of
larger grains or planetesimals in the circumstellar disc. We estimate the mass
of VLA1623B to be <0.15M$sol. We can place a lower limit to its size of ~30x7
AU, and an upper limit to its diameter of ~100AU. The longer wavelength data of
VLA1623B also have a spectral index of \alpha~0.6+/-0.3. The nature of VLA1623B
remains a matter of debate. It could be a binary companion to the protostar, or
a knot in the radio jet from VLA1623A.Comment: 7 pages, 3 figures, 1 table, accepted for publication in MNRA
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